Flexible formatting for universal storage device

ABSTRACT

The present invention relates to a record carrier, drive device and method of reading from or writing to the record carrier, wherein a predetermined navigation area (DN) is provided on said record carrier for storing at least one predetermined parameter specifying at least one of a logical format and an application format used on said record carrier. Thereby, a universal portable disc format can be provided, where a single disc can contain content in many formats from many different devices and all these content types can coexist. A clean separation of physical, logical and application level structures is thus possible without loosing any flexibility or ability of drive devices to maintain these structures.

The present invention relates to a record carrier, drive device andmethod of reading from or writing to the record carrier, such as anoptical disc. In particular, the invention relates to a standard logicalformat for an optical disc.

The applicant has recently developed a miniature optical disc thatrecords, plays back and erases data using the same precision blue lasersthat are being developed for the next generation of high-definition discbased video recorders. A system of the miniature optical disc is knownas SFFO (Small Form Factor Optical) or Portable Blue (PB) and shows thatit is possible to store 4 Gigabytes on a 3-cm-disc, and to make a drivedevice, that can read it reliably, as small as a memory card. The PBdisc will have a logical format that includes a standard file system,such as UDF (Universal Disc Format) as specified in the UDFspecification Revision 2.01 by Optical Storage Technology Association(OSTA) dated 3 Apr. 1998 or a later version.

Current optical disc formats have officially a strict separation betweenphysical layer, logical layer and application layer. However, until nowthe standardization of a new optical disc format started from anapplication. Consequently, the first versions of the format whereoptimized for a specific application, e.g. audio replay on CD, videoplayback on DVD and video recording on BD, even on the physical level.And as a result, the official separation of layers is not effectuated,complicating additions to and alterations of the standard.

One example is partitioning. The physical layer may offer largesubdivisions in the form of sessions or small ones in the form ofpackets, but at the logical level current optical disc formats offer aunified address space. This is fine as a rule but excluding thepossibility of having more than one logical partition was not necessary.

Another example is the presence of physical hard links. Especially forconsumer electronics (CE) devices the use of physical hard links can beuseful as it simplifies the device. However, by putting the physicaladdresses of such hard links in the standard, the evolution from aread-only published format to a incrementally written format is madeunnecessarily difficult.

In addition, allocation strategy support is not supported from thephysical level. As a result, drives cannot implement allocationstrategies optimal for the particular drive type in a straightforwardmanner.

It therefore took considerable effort to enable data storage andrecording on CD and DVD because these formats started out as read-onlyformats for an audio/visual application. Each time new features wereadded the original format was strained and this has lead to sub-optimalsolutions. By focusing on one application at the start immediately a lotof flexibility was lost unnecessarily.

Currently there are many storage solutions, e.g. Flash or Microdrive,that all use a standard interface. So, although the properties of thestorage devices are radically different, they can be usedinterchangeably with the same devices. The standard interface provides ablock interface to the application and the application chooses theformat of the data it records on disc. This approach has a significantadvantage in that it allows for the same storage devices to be used inmultiple host devices. The problem is that for removable drives, unlesssome special action is taken, the discs created in different hostdevices will not be exchangeable.

For PD it could be considered providing drives that conform to anexisting drive interface, e.g., Compact Flash. This would allow PB to beused in many existing products, such as still picture cameras. Havingaccess to such an existing installed base of customers is likely to spurthe initial adoption of PD. The drawback to this approach is that nocontrol is provided over what is written on the disc. In particular, theapplication can use any file system, so that exchanging discs betweendevices is in general not supported.

It is important to realize what this might mean for a user. The PD driveis attached to a still picture camera and some pictures are recorded,e.g., using JPEG. Then the PD disc is put into another device, whichunderstands JPEG, but this device cannot mount the file system from thedisc. For a non-expert user this is very confusing, as it appears thatthe content has been lost. A similar problem can occur with otherdevices that use a standard, if they are widely used.

In view of this, measures are required for enabling a standardization ofthe disc format in such a way that drive interfaces can provide an errorfree block device. In particular this requires standardizing defectmanagement and handling the potential problem of hot-spots, where theapplication overwrites the same location too many times.

It is an object of the present invention to provide a record carrier,method and drive device for providing a universal disc format that canbe standardized to a level which is independent of the application fileformat.

This object is achieved by a drive device as claimed in claim 1, by arecord carrier as claimed in claim 21, and by a reading or writingmethod as claimed in claim 26. Accordingly, a drive readable area isprovided which offers a space for at least one of logical levelstructures and application level structures. This space can be used tooffer a generic way for the storage of specific definitions of logicalformats and application formats.

With this approach, the disc format can be standardized to a levelindependent of the application file format. The goal here is to ensurethat when the record carrier is put into the drive device, the systemcan recognize the files on disc although it may not understand theactual file content. This means that files can be written on the recordcarrier in multiple formats, e.g. MP3 audio, JPEG pictures, recorded inmultiple devices and every application can see all the files. So, anaudio player is able to recognize the JPEG files and ignore them, whileaccidental deletion can be prevented. Hence, a universal portable discformat can be implemented, where a single record carrier can containcontent in many formats from many different devices and all thesecontent types can coexist, while specific low level optimizations forspecific applications are still possible.

It is however still possible to implement drive devices with a standardinterface, e.g. Compact Flash, as long as the connected device includesan application that writes the selected format to the disc or the drivedevice itself provides this functionality.

The least one predetermined parameter may comprise a disc descriptorinformation for specifying at least one of an identification of therecord carrier, a type of the record carrier, and parameters applying tosaid record carrier as a whole.

Furthermore, the least one predetermined parameter may comprise apartition descriptor information for specifying at least one of a natureof each partition on the record carrier, a type of each partition on therecord carrier, a space associated with each partition on the recordcarrier, a fragment allocation to each partition on the record carrier,and specific rules for recording on each partition on the recordcarrier.

In addition thereto, an application use area may be provided in thenavigation area for storing an application specific informationavailable to at least one of a physical layer, a logical layer and anapplication layer of the drive device.

Thus, by providing the above areas, a unique opportunity is given todesign the storage on the record carrier at a high degree of flexibilitynot known from previous standards. It offers an easy way for theaddition of logical level and application specific structures on thelowest level within the standard. It enables, for instance, drive leveloptimizations in the logical layer, general application optimizations inthe logical layer, and application specific optimizations in thephysical layer. As a result, an unprecedented flexibility in employingthe disc format and any future extensions is achieved, offering logicalpartitions, interleaved, fragmented, embedded and dynamically sizedpartitions, programmable physical hard links, allocation strategysupport, application configuration and optimizations, generalapplication support in the logical layer, scratch area for the drive,e.g. to record usage tracking for power optimizations, and a pointer andanchor pool, e.g. to speed up disc mounting.

The at least one parameter of the navigation area may be accessible byat least one of a logical layer and an application layer of the drivedevice by using a predetermined access command.

Furthermore, the access means may be arranged to provide a cachingfunction for caching at least a part of the information provided on thenavigation area, and/or to use pointers stored in the navigation areafor partitioning the record carrier into separate areas, and/or to usethe navigation area for determining the location of a starting addressnumber in the logical address space for the record carrier as a whole orfor a specific application, and/or for reserving space in a program areaof the record carrier for specific file systems, allocation classes orapplications, wherein properties or attributes can be assigned to thereserved space, and/or pointers into the reserved space and room forapplication specific data can be provided.

Additionally, the access means may be arranged to write to thenavigation area a location information of data accessed at a rate higherthan a predetermined number or an access pattern information forsequential data retrieval. A dynamic partitioning may be used fordefining areas in the navigation area.

The access means may be arranged to apply a volume-based rightsmanagement to sessions of an information area of the record carrier.Moreover, a volume-based, partition-based or fragment-based defectmanagement may be applied to the sessions of the information area of therecord carrier.

Moreover, pointers stored in the navigation area may be used forapplying a seeking function. This offers the opportunity for seekoptimization to limit power consumption.

Furthermore, the navigation area may be used for selecting anapplication class for an application.

In particular, the navigation area may be arranged in a lead in area ofthe information area of the record carrier. Then, sessions provided inthe information area can be written without separate lead-in andlead-out area. Furthermore, the sessions may have a granularity of onefragment and/or may have at least one of a varying size and a varyingphysical location.

The drive device may be a removable drive device for an optical disc.Furthermore, the drive device may comprises a standard interface forstorage devices, e.g. a PCMCIA, Compact Flash, Newcard, or MMCAinterface.

Further advantageous modifications are defined in the dependent claims.

The present invention will now be described on the basis of a preferredembodiment with reference to the accompanying drawings, in which:

FIG. 1 shows a schematic block diagram of a removable drive device witha standard interface and input function according to the preferredembodiments of the present invention;

FIG. 2 shows a schematic diagram of a logical format of an informationarea of an optical disc with a disc navigation area according to thepreferred embodiment;

FIG. 3 shows a schematic diagram of a logical format of a defaultprogram area referred to by a disc navigation area according to thepreferred embodiment;

FIG. 4 shows a schematic diagram of a logical format of an informationarea with a sample program area according to preferred embodiment;

FIG. 5 shows a schematic diagram of a logical format of an informationarea with an application reserved area according to preferredembodiment; and

FIG. 6 shows schematic diagrams of logical sample formats of differentaspects of partitioning according to the preferred embodiment.

The preferred embodiment will now be described in connection with aremovable PB drive device which exposes a FAT based CF-II interface tolegacy hosts such as a digital camera, a PDA or the like.

In connection with the present invention, the term “legacy” is used toindicate those formats, applications, data or devices, which have beeninherited from languages, platforms, and techniques earlier than thecurrent technology. Typically, the challenge is to keep the legacyfeatures or applications running or legacy devices supported whileconverting it to newer, more efficient features or devices that make useof new technology and skills.

A storage device needs a file system so that the data can be stored andretrieved as files. The most common file system for CD-ROM is ISO 9660which is the international standard version of the High Sierra Groupfile system and is designed for personal computers.

With the advent of the Digital Versatile Disc (DVD), the UDF file systemhas been added to the list. This is suitable for read-only, re-writable(RW) and recordable or write-once (R) discs and allows long file names,as for instance, the Joliett extension to ISO 9660. CD media requirespecial consideration due to their nature. CD was originally designedfor read-only applications which affects the way in which it is written.RW formatting consists of writing a lead-in, user data area, andlead-out. These areas may be written in any order.

Until recently, optical discs have not been used intensively as truerandom access devices. With the introduction of transparent defectmanagement and speed-up of read and write cycles for optical discs, thistype of use is expected to intensify. Multiple portable device types,e.g. video cameras or mobile phones, are expected to have PB drivedevices as primary storage.

In the following preferred embodiment, UDF is used as the PB filesystem.

FIG. 1 shows a removable drive device 30 adapted e.g. to fit the CompactFlash form factor. Hence, the drive device 30 can be used to replacesolid state memories. To achieve this, a standard CF-IL interface unit20 with corresponding connection terminals 32 is provided. Due to thefact that the CF interface unit 20 is commonly used in connection with aFAT file system, it must be arranged to map from FAT to UDF when writingto the disc 10 of the removable drive device 30, and to map from UDF toFAT when reading from the disc 10.

FAT is the MS-DOS file system supported by most of today's operatingsystems. It comes in three different types, i.e. FAT 12, FAT 16 and FAT32, wherein the names refer to the number of bits used by the entries inthe file allocation table which gave the file system its name. The fileallocation table is actually one of the structures inside the FAT filesystem as seen on-disc. The purpose of this table is to keep track ofwhich areas of the disc are available and which areas are in use. Thefile allocation table can be regarded as a singly linked list. Each ofthe chains in the file allocation table specifies which parts of thedisc belong to a given file or directory. The user data area is the areawhere the contents of the files and directories are stored.

According to the preferred embodiment, it is proposed to create a drivereadable area in the lead-in that offers a space for logical levelstructures and application level structures. This area is called thedrive navigation area (DN). This space is used to offer a generic wayfor the storage of specific definitions of logical formats andapplication formats. This disc navigation area DN can be used to providea standardized disc format to a level that it is independent of theapplication file format. Thereby, it can be assured that the system canrecognize the files on the disc 10 although it may not understand theactual file content. This means that files can be written on the disc 10in multiple formats, e.g. MP3 audio or JPEG pictures, recorded inmultiple devices and every application can see all the files.

The file system used by the application can be mapped by the interfaceunit 20 to the file system used on the disc 10. In this case the drivedevice 30 will present a block interface and the legacy application canuse the device as usual. However, software in the drive device 30 willdetect the file system the application is trying to use, e.g. FAT, andmap between it and the PB File System (UDF). This requires a lot ofintelligence and memory in the drive device 30 to perform this mapping.Essentially the interface unit 20 of the drive device 30 will presentthe expected file system to the application and then map any changes theapplication writes to the native file system. This approach ensures thehighest level of exchangeability but is the most complex.

As an alternative, the file system may be embedded in the basic formatfile system. In this case the file system used by the application can beembedded in the basic file system. The application file system willappear as a single file in the basic file format. This is less complexthan the first proposal but reduces exchangeability. Files stored in thebasic file system will not be seen by devices that use one of theembedded file systems and vice versa. Multiple different applicationfile systems can be supported and each embedded separately in the basicfile system. As an example, legacy file systems can be embedded withinthe PB file system (UDF). The legacy file systems then appear asindividual files within UDF.

As a further alternative, the application can be presented with alogical address space and can be embedded within the main file system.In this case the application is presented with a logical address space,just like a block device, and the application can write any data in thisaddress space. The drive device 30 makes no attempt to interpret thedata written to this logical address space. Any device that does notmount the basic file system will be presented with this logical addressspace and can write to it This means that different devices mayoverwrite the content stored by other applications, e.g. if they usedifferent file systems. The size of the logical address space is limitedby the free space in the main file system. As an example, a partitioncan be embedded in the PB file system. This partition will be presentedto legacy devices and they can write any data within that partition.

The basic disc format will allow partitioning so that one partition canbe assigned to the basic file system but a second partition can bepresented to legacy devices. Free space can be moved between the twopartitions dynamically, partitioning of the disc. One partition is usedfor the PB format (UDF) and another partition can be used to present ablock device to legacy devices. Free space can be dynamically movedbetween the two partitions.

The flexible logical format PB as defined in the disk navigation area DNallows for multiple content types to coexist on a single disc and allowmultiple devices to all read the same disc. In addition, legacy devicesthat are unaware of the PB format can also use PB discs.

FIGS. 2 to 6 show different volume structures or layouts of a logicalformat of an information area IA arranged on the spiral track providedon the optical disc 10, according to the preferred embodiment of thepresent invention. The information area IA provided on the optical disc10 consists of lead-in LI, program area PA, and lead-out LO.

According to FIG. 2, the lead-in LI includes the disc navigation area DNand a rights management area RM. It may also include a defect managementarea (not shown in FIG. 2). There are several types of genericstructures in the disc navigation area DN, including a disc descriptor(DD), partition descriptors (PD), and application use areas (AUA). Thedisc descriptor identifies the disc 10 and contains data on the disctype, as well as, specifying parameters applying to the disc as whole,e.g. size, fragment size. The partition descriptors describe the typeand nature of each partition on the disc 10 as well as the spaceassociated with the partition. The disc 10 is subdivided into fragments.Which fragments belong to which partition (if any) and whether specialrules apply to a partition is recorded in the partition descriptors.Partitions can be owned by applications. Application use areas are usedto store application specific data available to the physical, logical orapplication layer, e.g. physical hard links.

Table 1 shows a sample structure for a disc descriptor of a total sizeof 2048 bytes according to the preferred embodiment, wherein the asterix(*) indicates default values which may be provided by the standard.TABLE 1 Disc Descriptor Descriptor_ID 8 bits Disc_ID 32 bits Disc_Type16 bits [0] Flags read-only 1 bit [0] has_PD (partition descriptors) 1bit [0] has_AUA (application use areas) 1 bit [0] has_RM (rightsmanagement area) 1 bit [1] has_SP (sparing area) 1 bit [1]has_defectmanagement 1 bit [1] reserved 1 bit [0] reserved 1 bit [0]Reserved 8 bits [0] Fragment_size 16 bitsNumber_of_Partition_descriptors 16 bits [0]Number_of_Application_Use_descriptors 16 bits [0] Compliance_level 8bits Disc_description (text) 256 bytes Defect_table DT_begin 32 bit [*]DT_length 32 bit [*] Sparing_area SP_begin 32 bit [*] SP_length 32 bit[*] Reserved 1760 bytes Total size 2048 bytesThe fragment size determines the granularity of the virtual grid andtherefore determines the minimum extent size for partitioning.

Table 2 shows a sample structure for a partition descriptor of a totalsize of 2048 bytes according to the preferred embodiment, and tables 3and 4 show respective a sample values of an allocation class ID and adefect management type to be used in the partition descriptor. TABLE 2Partition Descriptor Descriptor_ID 8 bits Partition_ID 32 bitsPartition_type 16 bits Flags read-only 1 bit [0] has_allocation_class 1bit [0] has_application 1 bit [0] has_own_defectmanagement 1 bit [0]reserved 1 bit [0] reserved 1 bit [0] reserved 1 bit [0] reserved 1 bit[0] Compliance_level 8 bits Allocation_class_Id 8 bits [0]Appilcation_ID 16 bits [0] Reserved 24 bits [0] Partition_description(text) 256 bytes Defectmanagement_type 8 bits [0] Defect_table DT_begin32 bit [0] DT_length 32 bit [0] Sparing_area SP_begin 32 bit [0]SP_length 32 bit [0] Total_Size [bytes] 64 bits AllotmentNumber_of_Extents (n) 16 bits [1] for i = 1 to Number_of_Extents start_extent 32 bits  length_extent 32 bits next i Reserved 1750-n*8bytes Total size 2048 bytes

TABLE 3 Allocation_class_ID 0 Best Effort Data 8 Start-up files 9Volatile files 10 Robust files 16 Low bit rate streaming 17 Medium bitrate streaming 18 High bit rate streaming 24 Enhanced Multimedia Files

TABLE 4 Defectmanagement_type 0 no partition based defect management 1no defect management 2 partition specific area 3 fragment fringes

Table 5 shows a sample structure for an application use descriptor of atotal size of 512 bytes according to the preferred embodiment. TABLE 5Application Use Descriptor Descriptor_ID 8 bits Application_ID 32 bitsApplication_type 16 bits Flags read-only 1 bit [1]requires_authentication 1 bit [1] AUF_encrypted 1 bit [0] has_pointers 1bit [0] has_additional_sections 1 bit [0] has_partition 1 bit [0]reserved 1 bit [0] reserved 1 bit [0] Reserved 8 bits [0]Application_Use_desription (text) 256 bytes Partition_ID 32 bits [0]Number_of_additional_sections (n) 32 bits [0] Application_Use_Field ..bytes Total size 512 bytes

As an example, the parameter value Application_ID=0 may be reserved forthe drive device 30. The read-only flag pertains to unauthorizedapplications only. Furthermore, encryption can be performed by theapplication or by the drive device 30. If it is performed by theapplication, the parameter AUF_encrypted is set to zero.

All descriptors in the disk navigation area DN are, in principle,maintained by the drive device 30 and are accessible by the logicallayer with corresponding access commands, such as get_(—). . . 0 andwrite_(—). . . 0 commands, although not all fields may be accessible.The application use area can be accessed by applications withcorresponding access commends, e.g. get_(—). . . 0 and write_(—). . . 0commands. The access control is done by the logical layer.

The logical format of PB may start with a contiguous physical addressspace of at least 1 GB as delivered by the physical layer. Theprovisions may then enable the concurrent storage of a wide variety ofapplications and optimize for power consumption. Areas are collectionsof fragments which are collections of contiguous ECC (Error CorrectionCode) blocks, thus building a virtual grid. The fragment size may beoptimized for single transfer to/from buffers, e.g. 2-4 MB. Based ontheir own allocation rules, applications may allocate data in parts ormultiples of fragments. ECC blocks are collections of sectors. As astarting point, the PB ECC blocks and sectors may comply to the Blu-rayDisc standard. However, the ECC block size may be 32 KB.

The logical format will be able to abstract the properties of theoptical disc from the host. This means that defect management but alsopower efficiency measures, if any, can be implemented in the drivedevice 30.

Compared to traditional (CD) sessions the PB sessions can be withoutseparate lead-in and lead-out areas. Furthermore, they may have agranularity of one fragment and not necessarily need to be contiguous.Moreover, the sessions not necessarily need to be fixed regarding sizeand physical location after initialization, e.g. in case of a dynamicpartitioning. The sessions may have a volume based rights managementand/or a volume based, partition based or fragment based defectmanagement.

The disc navigation area DN, which may be considered an extended PMA[Program Memory Area as defined in Orange Book], can thus offer hooksfor describing sessions identity, content properties, with applicationspecific re-mapping pointers and room for configuration data.

The information area IA as shown e.g. in FIG. 2 consists of the lead-inarea LI, the lead-out LO area, the disc navigation area DN, the digitalrights management area RM, and the program area PA. The program area PAis subdivided into fragments of e.g. 64 ECC blocks of 32 KB (—2 MB). Ona 1 GB disc the disc navigation area DN and the rights management areaRM may consist of one fragment.

There may be a lead-in area LI outside of the logical address space toaid physical navigation to the begin of the address space. The lead-inarea may contain the address of the last physical block on the medium.This information may be stored in the disc navigation area DN. The discnavigation area DN and the rights management area RM are part of thelead-in area LI. Additionally, there is provided a (small) lead-out areaLO outside of the logical address space to aid physical navigation tothe end of the address space.

The disc navigation area DN may consist of e.g. 44 ECC blocks on theinside of the disc 10. As already mentioned, the disc navigation area DNis a space reserved for pointers and application specific data which canbe used by the interface unit 20 of FIG. 1 to access the disc 10. Thepointers in the disc navigation area DN can be used by the interfaceunit 20 to effectively partition the PB disc into separate areas. It canalso be used by the interface unit 20 to determine the location of theinitial address number 0 in the logical address space for the disc 10 asa whole or for a specific application. Furthermore, it can be used byfor reserving space in the program area for specific file systems,allocation classes or applications. Reserving can be either inclusive,i.e. allowing other uses, or exclusive, i.e. dedicated for one use only.Moreover, the disc navigation area DN can be used by the interface unit20 to assign properties or attributes to the reserved space, and/or toprovide pointers into the reserved space and room for applicationspecific data.

The area's defined in the disc navigation area DN are in units offragments but do not necessarily consist of contiguous sets offragments. Nor is the allocation of fragments to area's defined in thedisc navigation area fixed. A useful part of the disc navigation area DNshould be cacheable by the drive device 30, e.g. in a NVRAM/CID(Non-Volatile RAM/Chip In Disc). Examples of the use of the discnavigation area DN will be described below.

FIG. 3 shows a schematic diagram of a logical format of a defaultprogram area consisting of a Defect Management area (DM), a sparing area(SP), an area for user data and an area FS reserved for the file system.Note that these areas themselves are optional as are the locations ofthese areas. The starting points of the areas are recorded in the discnavigation area DN, as well as, optionally, their size.

FIG. 4 shows a schematic diagram of a logical format of the informationarea IA with a sample program area according to the preferredembodiment.

For certified allocations classes, specific areas can be reserved in theprogram area. Reserving space or area and assigning a allocation classare separate actions. The allocation class should be considered oneproperty of that area. Multiple allocation classes may be applicable toone area For each area defined in this manner separate allocationstrategies may apply. The allocation classes for areas are recorded inthe disc navigation area DN. Different allocation strategies apply tothe different allocation classes.

In general, from a perspective of limiting power consumption it isprobable optimal to allocate files that are read often towards theoutside of the disc 10 and files that are written often a little more tothe inside. File system data combines both aspects and should beallocated farthest to the outside.

The default allocation class is best effort data. This applies, forinstance, to the free space in the default program area. All space thatis not reserved is considered available to this class. By default thisclass has defect management by re-mapping. The defect management area DMand the sparing area SP are defined at the beginning of the area asdescribed above. The default starting location of the area BE availableto this class is on the inside of the disc.

Note that all areas are readable by a general purpose operating system(OS). Standard OS functionality can also write to the area BE availableto the best effort allocation class. To write to other areas a certifiedapplication is needed, which can also be part of the OS.

It is noted that the following allocation classes make sensespecifically if the drive operates using constant angular velocity(CAV). The latter means that the read/write speed on the outside of thedisc is more than 2 times that on the inside.

Start-up files are files that applications use to start their operationand that need to be read each time the application is started. Oneallocation class may be start-up files. An area SF for this class istypically located towards the outside of the disc for read speed. Anabstract may be cached in an NVRAM/CID for mount optimization orprevention. Separate pointers to start-up files may be recorded in thedisc navigation area DN.

Volatile files are files of a certain size that are written often, i.e.more than a predetermined number of times. An area VF for this class istypically located towards the outside of the disc 10 or write speed.Volatile files may need to be relocated. One strategy may be to relocatethe file each time it is written. The space reserved for volatile filesthen should be at least double of the expected combined size of thevolatile files.

Another option would be to record the allocation history of volatilefiles in the disc navigation area DN and re-allocating them if writtenas many times as half the expected recyclability of the medium.

Robust files are files that are to be stored in a manner not susceptibleto physical damage. This can be achieved by having companion areas oneon the inside of the disc and one, diametrically opposed on the outsideand writing the file to each area, i.e. physical distant mirroring.

Depending on the definition low bit rate streaming files may be writtenin an area LBR available for the best effort allocation class. The areaLBR for these file may be allocated to the inside of the disc 10 withreal-time file allocation or in the middle of the address space withre-mapping based defect management. Or put in another way, contiguous onthe inside and with limited fragmentation in the middle.

Depending on the definition it may be required to reserve an area for amedium bit rate streaming class with an allocation unit of, forinstance, twice the fragment size.

An area MBR for these files may be allocated in the middle of the disc10 with real-time file allocation or towards the outside of the discwith re-mapping based defect management. Toward the outside morefragmentation may be permissible.

Depending on the definition it may be required to reserve an area forhigh bit rate streaming class with an internal allocation units size ofseveral times the fragment size.

An area HBR for these files may be allocated in the middle of the disc10 with real-time file allocation or towards the outside of the discwith re-mapping based defect management.

Additionally, an area (not shown) may be provided for enhancedmultimedia files.

FIG. 5 shows a schematic diagram of a logical format of an informationarea with an application reserved area according to preferredembodiment.

All applications can use allocation classes as defined for a specificdisc. Certified or compliant applications can reserve an area APP forthemselves applying one of the existing allocation classes. Also thisarea APP may have certain properties like defect management.

Application specific data can be defined in the disc management area DN,e.g. multiple entry points into the data recorded for a specificapplication. This offers the opportunity to apply seek optimization,e.g. special access patterns, to limit the power consumption. For someapplications the drive device 30 may be able to select an applicationclass optimal for its purpose without the aid of the application.

Note that the host, drive device 30 or application may choose to recordin the disc navigation area DN the location of data that is oftenaccessed or record access patterns to optimize retrieval of data whichis often accessed in sequence, i.e. pre-emptive caching, or reallocatedata optimized for observed retrieval patterns.

FIG. 6 shows schematic diagrams of sample logical formats of differentaspects of partitioning. In particular, FIG. 6(a) shows an example oftwo straightforward logical partitions, where specific pointers or entrypoints are stored in the partition descriptor to define a firstpartition for a UDF file system, e.g. E:\, and a second partition for aFAT file system, e.g. F:\. Furthermore, FIG. 6(b) shows an example of aninterleaved partitioning with a plurality of partitions allocated to thefirst and second file system, respectively. FIG. 6(c) shows an exampleof an embedded partitioning, where the FAT file system appears asindividual files in the UDF file system. Finally, FIG. 6(d) shows anexample of dynamically sized partitions, where free space is dynamicallymoved between the two partitions of the FAT and UDF file systems.

The partitioning can be based on a virtual partitioning which refers toimplicit partitions which are not defined explicitly, i.e. shape,boarders and size of these data sub-regions are not prescribed but canchange dynamically, which leaves the choice for implementations to fitthe intended purpose. Further details concerning the virtual or implicitpartitioning can be gathered e.g. from document WO 01/95331 A2. Defectmanagement can be performed for each partition separately.

It is noted that the present application is not restricted to the abovespecific embodiments but can be used for any file system and disc formatof a drive device having an interface unit through which a host devicecan be connected. Moreover, any predetermined area on the disc can beused as a navigation area for storing logical level and/or applicationlevel data to provide the flexible disc format. The preferredembodiments may thus vary within the scope of the attached claims.

1. A drive device for providing access to a record carrier (10), saiddrive device (30) comprising access means (20) for providing at leastone of a read access and a write access to at least one predeterminedparameter written on a predetermined navigation area (DN) on said recordcarrier (10), said at least one predetermined parameter specifying atleast one of a logical format and an application format used on saidrecord carrier (10).
 2. A device according to claim 1, wherein said atleast one predetermined parameter comprises a disc descriptorinformation (DD) for specifying at least one of an identification ofsaid record carrier, a type of said record carrier, and parametersapplying to said record carrier as a whole.
 3. A device according toclaim 1, wherein said at least one predetermined parameter comprises apartition descriptor information (PD) for specifying at least one of anature of each partition on said record carrier, a type of eachpartition on said record carrier, a space associated with each partitionon said record carrier, a fragment allocation to each partition on saidrecord carrier, and specific rules for recording on each partition onsaid record carrier.
 4. A device according to claim 1, wherein saidaccess means (20) is configured to provide at least one of a read accessand a write access to an application use area (AUA) provided in saidnavigation area for storing an application specific informationavailable to at least one of a physical layer, a logical layer and anapplication layer of said drive device (30).
 5. A device according toclaim 1, wherein said at least one parameter of said navigation area(DN) is accessible by at least one of a logical layer and an applicationlayer of said drive device (30) by using a predetermined access command.6. A device according to claim 1, wherein said access means (20) isarranged to provide a caching function for caching at least a part ofthe information provided on said navigation area.
 7. A device accordingto claim 1, wherein said access means (20) is arranged to use pointersstored in said navigation area (DN) for partitioning said record carrier(10) into separate areas.
 8. A device according to claim 1, wherein saidaccess means (20) is arranged to use said navigation area (DN) fordetermining the location of a starting address number in the logicaladdress space for said record carrier (10) as a whole or for a specificapplication.
 9. A device according to claim 1, wherein said access means(20) is arranged to use said navigation area (DN) for reserving space ina program area of said record carrier (10) for specific file systems,allocation classes or applications.
 10. A device according to claim 9,wherein said access means (20) is arranged to use said navigation area(DN) for assigning properties or attributes to said reserved space. 11.A device according to claim 9, wherein said access means (20) isarranged to use said navigation area (DN) for providing pointers intosaid reserved space and room for application specific data.
 12. A deviceaccording to claim 1, wherein said access means (20) is arranged to usepointers stored in said navigation area (DN) for applying a seekingfunction.
 13. A device according to claim 1, wherein said access means(20) is arranged to use said navigation area (DN) for selecting anapplication class for an application.
 14. A device according to claim 1,wherein said access means (20) is arranged to write to said navigationarea (DN) a location information of data accessed at a rate higher thana predetermined number or an access pattern information for sequentialdata retrieval.
 15. A device according to claim 1, wherein said accessmeans (20) is arranged to use a dynamic partitioning for defining areasin said navigation area (DN).
 16. A device according to claim 1, whereinsaid access means (20) is arranged to apply a volume-based rightsmanagement to sessions of an information area (IA) of said recordcarrier (10).
 17. A device according to claim 1, wherein said accessmeans (20) is arranged to apply a volume-based, partition-based orfragment-based defect management to sessions of an information area (IA)of said record carrier (10).
 18. A device according to claim 1, whereinsaid drive device is a removable drive device (30) for an optical disc(10).
 19. A device according to claim 1, wherein said drive device (30)comprises a standard interface (32) for storage devices.
 20. A deviceaccording to claim 19, wherein said standard interface (32) is a PCMCIA,Compact Flash, Newcard, or MMCA interface.
 21. A record carrier forstoring data on an information area (IA) thereof, wherein saidinformation area comprises a navigation area (DN) for storing at leastone predetermined parameter specifying at least one of a logical formatand an application format used on said record carrier (10).
 22. A recordcarrier according to claim 21, wherein said navigation area (DN) isarranged in a lead in area (LI) of said information area (IA).
 23. Arecord carrier according to claim 21, wherein sessions provided in saidinformation area (IA) are written without separate lead-in and lead-outarea.
 24. A record carrier according to claim 21, wherein sessionsprovided in said information area (IA) have a granularity of onefragment.
 25. A record carrier according to claim 21, wherein sessionsprovided in said information area (IA) have at least one of a varyingsize and a varying physical location.
 26. A method of reading from orwriting to a record carrier (10), said method comprising the steps of:a) providing on said record carrier (10) a predetermined navigation area(DN); b) writing on said navigation area (DN) at least one predeterminedparameter specifying at least one of a logical format and an applicationformat used on said record carrier (10); and c) using said at least onepredetermined parameter for at least one of a read access and a writeaccess to said record carrier (10).